1. Field of the Invention
The present invention relates to a sample moving apparatus, a sample moving system and a semi-conductor manufacturing apparatus suitable for moving a sample which requires high-accurate positioning, such as a wafer for use in semiconductor manufacture.
In the mass production process of LSI chips, there is widely employed an exposure method based on the so-called step and repeat technique in which a circuit pattern is exposed to a wafer sequentially on the basis of shots one by one by repeatedly moving and positioning the wafer. This type exposure system requires a sample moving apparatus for moving and positioning wafers with high accuracy.
An XY-stage is generally used for such the sample moving apparatus. Improvement in array accuracy and stack accuracy of a pattern transcribed to wafers requires to improve positioning accuracy and moving accuracy of the XY-stage. In some cases, however, satisfactory accuracy is not always obtained due to limitations in machining accuracy of the XY-stage and performance of a positioning control device. In these cases, it is usual that a fine adjustment stage is stacked on the XY-stage to provide the so-called stacked type apparatus of coarse and fine adjustment, so as to compensate for error of the XY-stage by using the fine adjustment stage.
Recently, XY-stages have a tendency to become larger with an increase in a size of wafers, thereby making it more difficult to ensure high accuracy of the XY-stages. To solve this problem, in for example, Japanese Patent Unexamined Publication No. 62-252135 a method is proposed wherein a wafer chuck having almost the same size as that of an exposure shot and a wafer moving mechanism are provided, and a wafer is exposed in sequence while rechucking it by the wafer chuck for each shot.